Jewelry rope chain has, for decades, been made largely by hand, and will be first described. The basic construction element, or component, of rope chain of the prior art is an annular link formed of a solid wire, usually of precious metal, e.g., 14 karat gold. The annular link 10 is shown in FIGS. 1 and 2 of the drawings, and has an opening or gap 12 formed therein. The gap 12 has a narrowest dimension 17 at its inner diameter, and widens to its largest dimension at its outer diameter.
The solid wire forming the link 10 usually has flattened sides 13 and rounded ends 13a which give to the wire 10 a major diameter 14 and a minor wire diameter 15. The cross-section of the wire forming the link 10 may also be of generally circular cross-section. The opening 12 of link 10 is substantially larger than the minor wire diameter 15 and is slightly larger than the major diameter at its narrowest dimension 17.
The wire 10, while shown as a solid in FIGS. 1 and 2, may be hollow (See link 10a in FIGS. 3 and 4), but may otherwise be of the same configuration as FIGS. 1 and 2. The hollow wire link 10a obviously utilizes less gold than the solid wire link 10, but it is more costly to manufacture the hollow link 10a than a solid wire link 10.
The split wire links 10 (or 10a), in the prior art, are usually made from circular wire and the sides are flattened, and a multiplicity of such links are intertwined to form, in outward appearance, a double helix, as shown in FIG. 4, which double helix format is the standard rope chain 20 of the prior art. The standard rope chain of the prior art of FIG. 4 is made from the split wire links 10, as will now be described.
Each annular link 10 of the rope chain 20 has an inner diameter (D.sub.i) that is slightly over three times the major wire diameter 14, e.g., 3.4X. The first link 10 forming the rope chain will be termed herein the A1 link, so designated because it is the first link in the first of a series of four links.
The relative orientation of the links 10 forming the rope chain is important. The A1 link is initially oriented (manually) so that its opening, designated 12a, lies in a predetermined direction, e.g., facing generally upwardly, as in FIG. 5a. The second link of the A series, designated the A2 link, is passed through the opening 12a of the A1 link, with the opening 12b of the A2 link facing downwardly at about 180.degree. removed from the A1 link opening 12a, as shown in FIG. 5b. The A1 and A2 links are juxtaposed and intertwined so that they lay against each other, with the periphery of the A2 link lying against the periphery of the A1 link, to the greatest extent possible, thereby creating a relatively large central opening 30 within the pair of intertwined abutting annular A1, A2 links. The plane of the A1 link lies in parallel to the plane of the paper, and the plane of the A2 link is slightly skewed from the A1 plane.
The opening 12c of the third link, designated the A3 link, is then passed through the opening 12b of the A2 link and over the minor diameter of the A1 link and laid angularly against the A1 and A2 links, the opening 12c of the A3 link lying in the same orientation as the opening 12a of the A1 link, and as shown in FIG. 5c, but with its plane more greatly skewed than the A1 and A2 links. A central opening 30a still remains within the now three intertwined links A1, A2 and A3. The plane of each of the links differs from each other by perhaps about 20.degree. because their abutment is angular.
Turning now to FIG. 5d, the opening 12d of a fourth link, A4, is now passed over the A1, A2 and A3 links, through the central opening 32a, and thereby envelopes the A1, A2 and A3 links. The A4 link is laid against the other links (A1-A3) and its plane lies approximately 20.degree. from the plane of the A3 link. The opening 12d of the A4 link is disposed in the same orientation as the opening 12b of the A2 link.
All of the just-described manipulations are generally performed manually at the present time. As earlier mentioned, the openings 12a-12d of the annular links 10 are large enough to pass over the major and minor diameter of the wire forming the link. Further, the series of links just described, A1-A4, each having a D.sub.i of link slightly over three times the major wire diameter, permits the ready manual intertwining of links just described, especially the envelopment of the A4 link about the A1, A2 and A3 links.
The just-described intertwining and orientation of A1-A4 links permits the continuation of the intertwining of additional series of links (of four units each) to create a "double helix" rope chain 20 of a desired length. The adding on of an additional series of four links (designated herein as the B series) is a repetition of the orientation previously described with reference to the A1-A4 series, but the planes of the B series lie at approximately 90.degree. to the planes of the respective links in the A series.
Thus, the next link of the B series, designated the B1 link, has its opening 12e passing through the A1-A4 links, and abutting a solid portion of the A1 link, as shown in FIG. 5e. It will be noted that the orientation of the B1 link is at approximately 90.degree. to that of the A1 link, as shown in the cross-sectional view taken along line 6--6 of FIG. 5e. The respective openings 12A and 12e both face upwardly.
It is to be noted that, because of the slightly over three times D.sub.i of each annular link with respect to the major wire diameter, the B1 link can readily envelope the A2, A3 and A4 links and abut the solid portion of the A1 link.
The B2 link is then passed through downwardly facing opening 12b of the A2 link and oriented so that its opening 12f faces downwardly, and is further oriented to lie as flat as possible against the B1 link. The next link in the B series, the B3 link (not shown), will abut the solid portion of the A3 link, having its opening facing upwardly, and the B4 link will pass through the A4 opening (12d) and have the opening (of B4) facing downwardly.
The series of B links will lie in this general plane, i.e., at generally right angles to the first (A) series, and this type of right angle movement as the chain is built up results in a spiral having the appearance of the double helix, as shown in FIG. 4.
In the just-described build-up of annular links 10, it is to be noted that the openings of the first and third link additions abut the previous first and third links, and the second and fourth links pass through the openings of the previous second and fourth links. The openings of the previous second and fourth links were downwardly facing in the example shown in FIGS. 5a-5f, but could be differently oriented. However, the relative orientations of the links have, in the prior art, all been as just described. Insofar as the operator is concerned, he or she is always alternating an abutting connection (e.g., B1 abutting to A1 in the example) with the passing of a link through the second innermost hole of the link grouping (e.g., passing the B2 link through downwardly facing opening 12b of the A2 link).
After building up the links 10 in the manner just described, to form the double helix chain 20, the links are held in the desired juxtaposition temporarily by thin metal wire 22 wrapped about the links. Then solder S is intermittently applied, e.g., to every pair of adjacent links 10 at the external periphery thereof. The wire 22 is then removed. The intermittent soldering S (e.g., A2 to A3, and A4 to B1) results in a rope chain wherein every link pair is slightly movable, with respect to its adjacent link pairs, and results in a chain having the desired flexibility for forming a necklace or bracelet.
While the just described rope chain 20 of the prior art is extremely popular because of its appearance, it is costly to make, primarily because it utilizes a great deal of precious metal, such as 14 karat gold.
The applicants wish to also note the following prior art relating to the art of making rope chain, either manually or by machine, of which they are aware:
______________________________________ Registration No. Inventor ______________________________________ 848,299 Feid 979,110 Ungerer 1,053,726 Hamm 1,886,784 Boppenhausen 4,493,183 Bucetari 4,503,664 Allazzetta ______________________________________
It is a primary object of the present invention to substantially reduce the amount of precious metal required to make a rope chain (for equivalent width and length) vis-a-vis the prior art.